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Houston Department of Health and Human Services > Food Inspection and Safety (Consumer Health) > Food Safety Tips > Vegetables and Herbs in Oil

Vegetables and Herbs in Oil

People sometimes store various foods in oil to extend their shelf life and to flavor the oil. Some examples include garlic, onions, sun-dried tomatoes, hot peppers and mushrooms. These are popular products in the home prepared items category, are also prepared and sold commercially.

Incidents of food borne illnesses in recent years have increased the concern over the safety of such foods when stored in oil.

Why do these products present a health risk?

If stored at room temperature, they present a health risk. Vegetables are grown in the soil, and are naturally contaminated with Clostridium botulinum bacteria. These bacteria normally do not cause a problem unless they are in an air free environment such as a can or vacuum package. Surrounding the vegetables with oil creates an oxygen-free environment which is ripe for bacterial growth and toxin production. While refrigeration will slow down the growth of the bacteria, it may not prevent toxin production. Consuming products that contain these toxins can cause botulism, a potentially fatal food related illness. This illness can happen without any evidence of spoilage such as off odor, taste or appearance.

What are the symptoms of botulism?

The symptoms may include dizziness, blurred or double vision, difficulty in swallowing, breathing and speaking difficulties and progressive paralysis. The onset of symptoms takes approximately twelve to thirty-six hours and the duration may be one to ten days. Botulism can be fatal and can cause permanent neurological damage in those who survive.

How do we protect ourselves?

Do not use home-prepared or home-canned products. Be careful when you buy these products from fairs, farmers market or roadside vendors. If the products are prepared at the restaurant, discard after four hours at room temperature, using time as a public health control. According to recent changes in Texas Food Establishment Rules, use of time as a public health control must be properly documented. Commercially prepared products stored in oil that contain an acid (such as vinegar) or salts in their list of ingredients are generally considered to be safe. They are processed using technology not commonly available to consumers. All products must be refrigerated after opening and between each use. Feel free to contact the manufacturer if you are in doubt about the ingredients.

For more information about this article, or any other information, please call the Bureau of Consumer Health Services, at 713-794-9200.

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